// --------------------------------------------------------------------------------------------------------------------
// <copyright file="Forwarder.cs" company="Microsoft Corporation">
// The MIT License (MIT)
// 
// Copyright (c) 2014, Microsoft Corporation
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
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//  copies of the Software, and to permit persons to whom the Software is
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// The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
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// --------------------------------------------------------------------------------------------------------------------
namespace Microsoft.Robotics.Runtime
{
    using System.Threading;

    /// <summary>
    /// A strong-typed forwarder that simply passes the message along to a weakly-typed forwarder.
    /// This makes it possible to forward a message of one type to a receiver that exposes messages of another type.
    /// </summary>
    /// <typeparam name="TMessage">The type of message to forward.</typeparam>
    internal class Forwarder<TMessage> : BaseForwarder<TMessage>
        where TMessage : AgentMessage
    {
        /// <summary>
        /// The weakly-typed forwarder that accepts messages posted to this forwarder.
        /// </summary>
        private IForwarder nextHop;

        /// <summary>
        /// Initializes a new instance of the Forwarder class.
        /// It creates a strong-typed forwarder from a weakly-typed one.
        /// </summary>
        /// <param name="nextHop">
        /// The weakly-typed forwarder to forward to.
        /// </param>
        /// <param name="pipelineCreationTime">The time when the pipeline was created. This is used as the time origin for all timestamps.</param>
        /// <param name="creatingPipelineElementName"> Name of the pipeline element that created the forwarder.</param>
        public Forwarder(IForwarder nextHop, long pipelineCreationTime, string creatingPipelineElementName)
            : base(pipelineCreationTime, creatingPipelineElementName)
        {
            this.nextHop = nextHop;
        }

        /// <summary>
        /// Accepts and forwards a message of the given type.
        /// </summary>
        /// <param name="message">Message to forward/</param>
        /// <param name="blockUntilDelivered">
        /// If true, the call blocks if the message cannot be consumed, e.g. because an older message is waiting to be delivered. 
        /// The default behavior is "fire and forget", e.g. to replace the older message.
        /// </param>
        public override void Post(TMessage message, bool blockUntilDelivered = false)
        {
            this.ApplyTimestamp(message);
            this.nextHop.Post((object)message, blockUntilDelivered);
        }
    }
}
